MEDI7212 Lecture Notes - Lecture 4: Locus Coeruleus, Prefrontal Cortex, Proprioception
Document Summary
Transduction external noxious energy is converted into electrophysiological activity: nociceptors are free, unencapsulated, peripheral nerve endings found in most tissues (skin, deep somatic tissue, viscera, nociceptors respond to noxious stimuli, 3 types of noxious stimuli. Thermal: thermo-transduction, trpv1 - noxious heat, trpa1 - noxious cold. Transmission coded information is relayed via spinal cord to brainstem and thalamus: primary afferent neurons enter the spinal cord via dorsal root ganglion to synapse with second order neurons in dorsal horn. Sometimes, interneurons will convert non-nociceptive stimuli into nociceptive stimuli via white dynamic range neurons acting pathologically: white matter (axons ascending or descending the brain, major ascending tracts. Several nociceptive nuclei in thalamus project to multiple cortical areas (somatosensory cortices, anterior cingulate & insular: neocortical, somatosensory, anterior cingulate. "sensory -discriminative" = sense of intensity, location, quality and duration of pain. "affective-motivational" = unpleasantness and urge to escape that feeling. "cognitive-evaluative" = cognitions such as appraisal, cultural values, distraction and hypnotic suggestion.
